1. Field of the Invention
The present invention relates to a data communication apparatus and, more particularly, to a data communication apparatus for performing data communication through a line.
2. Related Background Art
In a conventional apparatus of this type, e.g., a facsimile apparatus for communicating image data, an automatic outgoing/incoming mode for automatically transmitting/receiving data, and a manual outgoing/incoming mode for manually transmitting/receiving data are known.
In an automatic incoming mode, when a calling signal is received, a line is automatically connected to a facsimile circuit to perform facsimile reception. In this case, if a calling party is a voice terminal such as a telephone set, voice communication cannot be performed.
Some conventional facsimile apparatuses having a message record function also have a voice communication function of making a voice response using a prerecorded voice message in an automatic reception mode to request facsimile transmission or to record a voice message from a calling party.
A control method executed when facsimile communication is started by a conventional manual operation will be explained below.
For example, manual transmission wherein after a telephone set is set in an off-hook state to manually call a given destination and a line is connected to the called destination, an original is set on a reader unit of a facsimile apparatus (e.g., a CCITT recommendation G3 facsimile) and a start key is depressed will be considered.
After the depression of the start key, the facsimile apparatus waits for a command sent from a receiver (destination) for a maximum of a T1 timer time (35 sec.+-.5 sec). This command is an initial recognition signal sent from the destination, i.e., a signal (NSF/CSI/DIS signal) indicating a communication function of the receiver side.
Facsimile communication is started only when the receiver is set in, e.g., a facsimile/telephone automatic selection mode, and outputs a CNG signal within a predetermined period of time after a voice response. When the CNG signal cannot be detected within the predetermined period of time, it is determined that the destination is in communication, and an operator call is made. In this case, when a transmitter performs manual transmission, facsimile communication cannot be started. When an operator on the receiver side does not respond to the operator call, facsimile communication is disabled. Even when the operator on the receiver side responds, he or she may often not depress a start key to start a reception operation since no sound can be heard from the transmitter side.
The automatic incoming mode of the conventional facsimile apparatus will be examined in detail below. In a facsimile apparatus having a telephone/facsimile automatic selection function and a message record function, a large number of incoming modes are available as follows.
In an apparatus of this type, first, a telephone mode is available. In this mode, an incoming tone is generated using a bell circuit when an incoming signal is detected. When an operator takes up a handset, a line is connected to a transmitter side. When a calling party wants speech communication, speech communication is performed in this state. When a calling party wants facsimile communication, an operator depresses a start key.
Second, a facsimile mode is known. In this mode, when an incoming signal is detected, a facsimile apparatus performs an automatic incoming operation. In some facsimile apparatuses, a time from detection of an incoming signal until the automatic incoming operation is executed can be set. More specifically, an incoming tone is generated by a bell circuit within a setup time after detection of the incoming signal, and an incoming operation can be manually started.
Third, a message record mode is available. In this mode, when an incoming signal is detected, a voice message "This is connected to a message phone. Please leave a message to record after a beep tone. Thank you. " is sent onto a line, and a calling party sends a voice message to be recorded after the beep tone.
Fourth, a facsimile/telephone automatic selection mode is available. In this mode, upon detection of an incoming signal, an apparatus responds using a message "This is ooo. Please start transmission if you want FAX communication or please talk after a beep tone if you want speech communication." When a calling party uses a facsimile apparatus, an automatic incoming operation is performed upon detection of a facsimile calling signal. If a calling party uses a telephone set, since a ringing tone is generated or a calling party's voice is sent from a loudspeaker, an operator can know that a telephone call is received. This mode belongs to the facsimile/telephone automatic selection mode.
Fifth, a facsimile/message record automatic selection mode is available. In this mode, upon detection of an incoming signal, an apparatus responds using a message "This is xxx. I am not at home now. Please start transmission if you want FAX communication or please leave a message to record after a beep tone." When a calling party uses a facsimile apparatus, an automatic incoming operation is performed. When a calling party uses a telephone, a message record mode is started.
For example, an apparatus can have the above-mentioned five modes, and these modes are selected by switches to change an operation upon detection of an incoming signal.
However, when a receiver side is set in the telephone/facsimile automatic selection mode, if a transmitter side performs manual transmission, facsimile communication cannot often be established. This is a serious drawback.
In an incoming operation mode, the telephone/facsimile/message record mode may be fixed or automatically selected as described above. In order to perform facsimile communication once the message record mode has been started, a special DTMF key is often depressed. However, a DTMF code is not standardized, and when a transmitter side does not have a DTMF transmission function, it is impossible to switch these modes.
Note that as applications associated with the telephone/facsimile automatic selection mode, U.S. Pat. No. 4,677,660, U.S. Pat. No. 4,815,121, U.S. Pat. No. 4,800,439, U.S. Pat. No. 4,932,048 and U.S. Pat. No. 4,916,607, and the like are known.
As applications associated with a speech communication/facsimile selection mode, U.S. Pat. No. 4,353,097 and U.S. Pat. No. 4,773,080 are known.